1. Field of the Invention
This invention relates to SiC-Al.sub.2 O.sub.3 composite sintered bodies and a method of producing the same, and more particularly to SiC-Al.sub.2 O.sub.3 composite sintered bodies suitable for use in structural materials having high strength and toughness and a method of producing the same.
2. Related Art Statement
Al.sub.2 O.sub.3 is widely used as a substrate or a package for a integrated circuit, a chip for cutting tool or a refractory material. However, the strength and toughness of Al.sub.2 O.sub.3 are low as compared with those of a silicon nitride sintered body, so that there is a restriction in the use as a structural material for engine parts and the like.
In order to increase the strength and toughness of Al.sub.2 O.sub.3, it has been proposed to disperse SiC particles or SiC whiskers into the Al.sub.2 O.sub.3 matrix. For example, the increase of the toughness in the Al.sub.2 O.sub.3 sintered body through the dispersion of SiC whiskers is disclosed in American Ceramics Society Bulletin, 64 [2], 298-304 (1985). Furthermore, the increase of the strength, toughness and hardness and the improvement of high temperature properties in the Al.sub.2 O.sub.3 sintered body through the dispersion of SiC particles are disclosed in Japanese Patent laid open No. 59-3,766, No. 61-21,964 and No. 61-174,165.
However, when only SiC whiskers are dispersed into the Al.sub.2 O.sub.3, matrix the sinterability of Al.sub.2 O.sub.3 is considerably damaged, and also the firing at a high temperature for a long time is required for the densification. For this end, SiC grains grow in the Al.sub.2 O.sub.3 sintered body to increase the toughness, but the strength undesirably lowers. On the other hand, the dispersion of SiC particles can not increase the toughness as compared with the case of dispersing SiC whiskers.